Speed of a boat in standing water is 9 kmph and the speed of the stream is 1.5 kmph. A man rows to a place at a distance of 105 km and comes back to the starting point. The total time taken by him is:

A. 16 hours

B. 18 hours

C. 20 hours

D. 24 hours

Answer: Option D

Solution(By Examveda Team)

Speed upstream = 7.5 kmph
Speed downstream = 10.5 kmph
∴ Total time taken
= $$\left( {\frac{{105}}{{7.5}} + \frac{{105}}{{10.5}}} \right)$$   hours
= 24 hours